An international team of astronomers has observed GS-10578, nicknamed "Pablo's galaxy," a massive galaxy almost identical to the Milky Way. This galaxy is now considered "dead" because its star formation seems to have stopped.
The supermassive black hole at its core is thought to be directly responsible for this phenomenon. By pulling in and then expelling gas winds at dizzying speeds, around 1,000 kilometers per second (about 620 miles per second), it ejects immense amounts of matter from the galaxy. However, these gases are essential for the formation of new stars. Deprived of this stellar fuel, the galaxy can no longer create new stars, condemning it to a slow death.
This discovery, published in
Nature Astronomy, had never been confirmed with such precision before the use of the James Webb telescope. Astrophysicist Francesco D'Eugenio notes that the observations reveal massive amounts of cold, dark gas, invisible to other instruments.
The gases expelled by the black hole escape at a speed sufficient to break free from the galaxy's gravitational attraction, thus dooming the formation of future stars. Theoretical models had suggested that a black hole could kill a galaxy by halting its star production, but this is the first time it has been proven with real data.
Roberto Maiolino, co-author of the study, points out that this discovery sheds new light on how black holes affect their host galaxy, without necessarily altering its structure. The next observations from the ALMA network will target the colder gases to determine whether hidden pockets of matter could still fuel star formation in this region.
What is a supermassive black hole?
A supermassive black hole is a celestial object located at the center of most galaxies, whose mass can reach several million or even billions of times that of the Sun. Unlike stars or planets, these black holes emit no light of their own because their gravitational pull is so intense that even light cannot escape from them.
Supermassive black holes likely form from expanding galaxies. They grow by absorbing surrounding matter, such as gas or stars, thereby increasing their mass. They are often responsible for extreme phenomena in galaxies, including expelling high-velocity gases that disturb star formation.
How do black holes affect star formation in galaxies?
Supermassive black holes can halt star formation by ejecting the gas necessary for this process. This gas, primarily composed of hydrogen, is the fundamental element needed to create new stars in a galaxy. When a black hole expels this gas at very high speeds, it pushes it beyond the galaxy's gravitational limits.
These gas winds expelled by black holes are often generated during their accretion phase. At this moment, the black hole pulls in immense amounts of matter and releases enough energy to eject this gas. Without this element, the galaxy loses its ability to form new stars, dooming it to become inactive or "dead."
Thus, black holes act as regulators of the lifecycle of galaxies, indirectly controlling the birth of new stars and influencing galactic evolution over billions of years.
Article by: Cédric DEPOND